Firm Shifts are Gone

Changed the filter in the C4 today & after finished noticed that the firm, crisp shifts are gone. What happened. Had a shift kit on it & I could chirp the tires on each shift now it won't do it. It's shifting like a new ford sedan now. What could I have done wrong? I know this spring & rod fell out, when I removed the filter. Maybe I put in back in wrong. I put the spring in first with the slim end of the rod next. Would that damage the C4 if in wrong? Not sure what it is.

I used ATF Type FA. On the back of the bottle it did say mets Fords specifications. Also, when I called TCI about the trannny since it was from them, they said I could use any type of fluid. Does the wrong fluid cause a problem like this?